Structural ceramic materials generally show many advantages in high performance materials applications because of their high mechanical strength and hardness properties and low weight. These features make many of these ceramic materials attractive for use in military applications such as armor for vehicles. Numerous non-military applications for these materials are just beginning to be explored and implemented.
Unfortunately, a major disadvantage of most structural ceramic materials is high cost. High cost limits the use of these materials both in military and non-military applications.
The high cost of many structural ceramics may be partly attributed to high cost of the starting ceramic powders which are to be shaped and densified to form structural ceramic parts. The starting powders are often made by energy-intensive processes or by other expensive methods adapted to produce high purity starting powders. Generally, it has been preferred to minimize the impurity contents of starting powders in order to maximize the performance of the ultimate ceramic part.
Some prior art processes have used chemical reactions in the formation of ceramic composites. In U.S. Pat. No. 4,879,262, B.sub.4 C-TiB.sub.2 composites were prepared by forming a powder compact containing B, C, and Ti or hydride or oxide powders thereof. The mixture was then combusted to yield a B.sub.4 C-TiB.sub.2. The reactants used in that process still entail substantial cost. Moreover, there is no apparent disclosure in the prior art showing the production of Al.sub.2 O.sub.3 -SiC-B.sub.4 C composites which have advantageous properties for armor applications.
Needless to say, it would be highly desirable to reduce these costs associated with structural ceramics. Indeed, reduction of cost is necessary if structural ceramics are to be used in broader non-military applications.